POS1248 OVERALL SURVIVAL, PROGRESSION-FREE SURVIVAL AND RELAPSE RATES ARE SIMILAR IN FEMALES VERSUS MALES UNDERGOING AUTOLOGOUS HEMATOPOIETIC STEM CELL TRANSPLANTATION (HSCT) FOR AUTOIMMUNE DISEASE
Authors: M. G. Birck, T. Alexander, M. Labopin, R. Greco, M. Badoglio, J. Snowden, A. Sureda Balari, A. Uuema, A. Van Biezen, J. R. Lavoie, J. Gao, A. Neville, C. S Moura, S. Bernatsky
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Autologous HSCT has been increasingly used for over 25 years to treat refractory autoimmune diseases (ADs). Multiple sclerosis (MS) and systemic sclerosis (SSc) cover around 80% of transplants performed for ADs<sup>[1]</sup>, where HSCT has become an integral and standard-of-care part of treatment algorithms. In a first European Society for Blood and Marrow Transplantation (EBMT) analysis of HSCT performed between 2010 and 2015, there was chronological improvement in outcomes (i.e., progression-free survival, relapse/progression, and transplant-related mortality), strictly connected to the transplant center experience, patient selection and progress with supportive care.<sup>[2]</sup> Here, trends and outcomes have been updated to include HSCT performed for ADs between 2015 and 2020. <h3>Objectives</h3> To describe outcomes of autologous HSCT for ADs, 2 and 5 years from transplant. <h3>Methods</h3> This is a retrospective study on data routinely reported to EBMT's Autoimmune Diseases Working Party (ADWP) registry, based on 247 centers in 40 countries and others (Italy, Germany, Sweden, United Kingdom, Netherlands, Spain, France, and Australia account for ~75% of cases). We included adult patients (≥18 years) undergoing autologous HSCT for ADs between 2015-2020. Patients without information on follow-up after HSCT were excluded. The date of the transplant was the starting point for all time-to-event analysis, and individuals with no event were censored at the date of the last follow-up. Successful initial engraftment was defined as achieving a neutrophil white cell count ≥ 0.5 × 10<sup>9</sup>/L for three consecutive days. We used Kaplan-Meier curves to evaluate overall survival (time until death) and progression-free survival (PFS) - defined as time to either relapse/progression or death. We also determined the cumulative incidence of AD relapse. <h3>Results</h3> We studied 1,389 individuals with ADs undergoing autologous HSCT from peripheral blood cell sources. The median follow-up was 26 months. Individuals were mostly female (58%), at a median age of 40 years (interquartile range 32.4-48.6). The main indications for HSCT included MS (68%) and SSc (21%). Successful initial engraftment occurred in the vast majority (98.5%), most times within 30 days from transplant. We observed 70 deaths (5% of 1,389), most (57, 81%) occurring within 2 years. Deaths were most often caused by AD relapse/progression (27%) or infection (24%). At 2 years post-transplant, overall survival was 95.5% (95% CI 94.2-96.5%), PFS was 82% (95% CI 79.6-84.2%), and relapse of AD occurred in 14.8% (95% CI 12.7-17.0%). Non-relapse mortality was 3.2% (2.3 - 4.3) at 2 years. Similar overall survival, PFS, and relapse rates were found for females versus males (biological sex at birth) at both 2 and 5 years post-HSCT (Table 1). Multivariate analysis was not done due to the heterogeneity of the population and the limited number of events. <h3>Conclusion</h3> Autologous HSCT for autoimmune disease results in high survival and moderately low relapse. Limitations include inadequate precision to stratify by autoimmune disease and transplant regimens. <h3>References</h3> [1]Alexander and Greco, BMT 2022 [2]Snowden et al., Blood Adv 2017 <h3>Acknowledgements</h3> The data originate from the EBMT registry. <h3>Disclosure of Interests</h3> None Declared.